Because cancer is second only to heart and vascular diseases as a cause of death in man, considerable effort and research has been expended in developing some form of chemotherapy to successfully treat the various kinds of human cancers. Tumors, one common manifestation of cancer in man, which are abnormal masses of new tissue growth, can bring physical discomfort and drain the body of its vital energies.
Many of the antitumor compounds recently discovered have been natural products. These include heterocyclic lactams from marine sponges (U.S. Pat. No. 4,729,996), succinimide derivatives of indole alkaloids (U.S. Pat. No. 4,667,030) and indoledione derivatives from marine sponges (U.S. Pat. No. 4,731,366). Antitumor activity has also been found in synthetic acylurea derivatives (U.S. Pat. No. 4,677,111).
U.S. Pat. No. 4,563,527 claims a series of naphthyl amidines as antitrypsin, anti-plasmin, anti-kallikrein and anti-thrombin agents.